I'm interested in buying this cap but I'm not sure its such a good idea...

I currently still have ammonia and nitrates in the trace range (tonights test actually showed 0 nitrate and trace amm, which I find odd) and I havent been able to get an RO/DI unit. It will take weeks for me to slowly change over to RO/DI anyway

I dont want to hold up the sale of this coral to others if its not a good idea for me now, but I dont know enough about them to make up my mind

thanks for any help